RESPOSTA DO FEIJÃO DE ALTA PRODUTIVIDADE AO NITROGÊNIO NO SISTEMA DE INTEGRAÇÃO LAVOURA-PECUÁRIA EM EXPERIMENTO DE LONGA DURAÇÃO

Abstract

Most areas of Brazil Subtropical region remains fallow during the winter period, as there are few viable alternatives to agricultural exploration in this period, which favors soil degradation events. Among the alternatives, cites to integrated crop-livestock (ICL) that with the production of pasture and sheep in winter and bean production in the summer, is an option that can solve the problems caused by fallow and make sustainable systems of agricultural production. This study aims to determine the long-term effects of grazing and increasing doses of nitrogen applied in winter pasture and bean crops, on yield and yield components of bean crop in the ICL system. The experiment lasted five different growing seasons (2006/07, 2008/09, 2010/11, 2012/13 and 2014/15). The experimental design was split split plot with three replications. In the main plot four doses of N in winter (0, 75, 150 and 225 kg ha-1), in the subplot the presence or absence of grazing and split split plot doses of N in the summer (0, 60, 120, 180 and 240 kg ha-1) applied to cover the bean crop, the source of N used was urea (45% N). It was observed that grazing did not affect grain yield, demystifying this would damage the system. It was found along the crops that the N applied in the winter period influenced significantly the bean crop productivity in succession, which shows the residual effect of nitrogen. It is also noted that, while it increases the N levels applied to bean plants, reduces the residual effect of N was applied on the winter grass, is often deleted in higher doses studied. The yield components studied were positively influenced by N doses in the summer. In the pooled analysis of five growing seasons, it was found that the expression of increased productivity for the bean crop was for application of 139 kg ha-1 of N in the winter culture combined with the use of 159 kg ha-1 of N in the summer.